Heretofore, since the information-recording devices such as HDD where a disk having recorded information is rotated possess moving parts, e.g., a motor to rotate the disk and a head to read and write information on the disk, vibration generated from themselves and vibration and sound leaked out of the devices through sympathetic vibration of the other parts derived from the vibration of the moving parts become a big problem. With regard to the motor, a remarkable improvement in vibration and sound has been achieved by changing a conventional bearing system into a fluid dynamic bearing but the improvement is not perfect.
Accordingly, an article like an aluminum tape, a metal plate made of, e.g., aluminum or stainless steel, a common vulcanized rubber sheet, or the like is adhered as a damping material to the devices themselves with an adhesive or a double-faced adhesive tape. Moreover, vibration damping becomes an important problem in compact and lightweight devices, for example, optical disks such as mini-disk and DVD, and compact videos. For solving such problems, there have been proposed a damping material using a specific thermoplastic material (JP-A-9-235477) and a damping material comprising a styrene-vinylisoprene-styrene block copolymer, a thermoplastic material, and a softener (JP-A-10-204249).
With regard to the above damping and soundproofing materials, a damping and soundproofing material having a desired shape is in principle obtained from a sheet-shape article by stamping out with a trimming die, but the trimming die is expensive, so that the cost of the damping and soundproofing material becomes high as a natural consequence in the case that the required number of the damping and soundproofing material is small. In the case of precision devices, since a trouble may arise when minute dusts invade inside the devices, individual parts are washed prior to their assembling. When the damping material is adhered with an adhesive or a double-faced adhesive tape, a member to which the damping material is adhered is washed in order to remove dusts attached at the adhesion process, but there arises a problem that detergent liquid penetrates into the adhesive layer and some troubles may be caused later. For avoiding this problem, the washing is sometimes not carried out, but in that case, non-washing may also cause staining of the precision devices.
Further, the use of a metal plate, especially stainless steel plate as a damping and soundproofing material is not adequate for the devices to be lightweight owing to the weight. In the case of vulcanized rubber sheets, when the thickness is thinned for saving weight and size, the strength of the sheets decreases and they are easy to be damaged at the molding, so that it is difficult to increase productivity. In addition, there is a fear that sulfur of a vulcanizing agent may remain and affect electronic parts. Moreover, with regard to silicone rubbers, there is a problem that staining of electrical contact points with a low molecular weight siloxane may be generate.
Furthermore, since the damping materials disclosed in JP-A-9-235477 and JP-A-10-204249 are necessarily molded thermally using an injection molding machine or the like, there is a problem similar to the case of the above rubber sheets that a damping layer should be formed beforehand and be bonded to a substance to be adhered when the damping layer cannot be formed directly to the substance to be adhered depending on the material and shape of the substance to be adhered.